JP2017084495A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery that can suppress irregularity of the activity of an active material in a layer of the active material of one electrode of positive and negative electrodes, which is parallel to a current collector of the other electrode.SOLUTION: A secondary battery includes a positive electrode 21a having a plate-like positive electrode current collector and negative electrodes 22a, 22b having plate-like negative electrode current collectors 25a, 25b. A plurality of positive and negative electrodes are alternately laminated one by one. The negative electrode current collectors 25a and 25b are formed of metal plates having through-holes 15a to 15d. The through-holes 15a to 15d are provided on the metal plate at a predetermined interval with respect to a predetermined alignment direction 20. In the secondary battery, the through-holes 15a to 15d provided to each of the negative electrodes 22a, 22b are arranged to be staggered in the alignment direction 20 in the pair of the adjacent negative electrodes 22a, 22b between which the positive electrode 21a is sandwiched.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a secondary battery.

  Patent Documents 1-3 describe a current collector for a secondary battery. Such a current collector is made of a mesh plate. The mesh plate is a perforated metal plate.

Japanese Patent Laid-Open No. 06-041055 Japanese Patent Application Laid-Open No. 09-120819 JP 2003-317723 A

  The inventors have found the following problems. That is, the hole provided in the current collector has a space between the adjacent hole. Therefore, the active material facing the hole is farther from the current collector than the active material facing the remaining metal plate around the hole. The distance from the current collector affects the function of the active material. For this reason, in the layer of the active material parallel to the current collector, the function of the active material is uneven.

  The present invention provides a secondary battery comprising at least one of a positive electrode current collector and a negative electrode current collector made of a metal plate having a through hole. An object of the present invention is to suppress unevenness of the function of the active material in the active material layer of the other electrode parallel to the current collector of at least one of the positive electrode and the negative electrode.

  One embodiment of the present invention is a secondary battery including a positive electrode having a plate-like positive electrode current collector and a negative electrode having a plate-like negative electrode current collector. The plurality of positive electrodes and the plurality of negative electrodes are alternately stacked one by one. At least one of the positive electrode current collector and the negative electrode current collector is made of a metal plate having a through hole. The through holes are provided at regular intervals on the metal plate with respect to a predetermined alignment direction.

  In the secondary battery, at least one of the following is satisfied; in the set of the negative electrodes adjacent to each other across the positive electrode, the through-holes provided in the negative electrodes are staggered in the alignment direction. And in the set of positive electrodes adjacent to each other across the negative electrode, the through holes provided in each positive electrode are staggered in the alignment direction.

  According to the present invention, an object of the present invention is to suppress unevenness of the active material in the active material layer of the other electrode parallel to the current collector of at least one of the positive electrode and the negative electrode.

It is an expanded sectional view of the positive electrode and negative electrode which concern on embodiment. It is sectional drawing of the positive electrode and negative electrode which concern on embodiment. 1 is a perspective view of a secondary battery according to Example 1. FIG. 3 is a plan view of a metal plate according to Example 1. FIG. It is an expanded sectional view of the positive electrode and negative electrode which concern on a comparative example. 6 is a plan view of a metal plate according to Embodiment 2. FIG. 6 is a plan view of a metal plate according to Embodiment 3. FIG. 6 is a plan view of a metal plate according to Example 4. FIG. 10 is a plan view of a metal plate according to Embodiment 5. FIG. 10 is a plan view of a metal plate according to Example 6. FIG. 10 is a plan view of a metal plate according to Example 7. FIG. It is an element division figure concerning simulation analysis. It is a graph showing the resistance value derived | led-out by simulation analysis.

  In the following description, the same components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is an enlarged cross-sectional view of the positive electrode 21a and the negative electrodes 22a and 22b. The secondary battery according to the present embodiment includes a positive electrode 21a and negative electrodes 22a and 22b. The pair of negative electrodes 22a and 22b face each other across the positive electrode 21a. The pair of negative electrodes 22a and 22b are adjacent to each other with the positive electrode 21a interposed therebetween.

  The secondary battery shown in FIG. 1 further includes separators 23a and 23b. The separator 23a isolates the positive electrode 21a and the negative electrode 22a. The separator 23b isolates the positive electrode 21a and the negative electrode 22a.

  The positive electrode current collector which the positive electrode 21a shown in FIG. 1 has is made of a metal porous body. The positive electrodes 21a and 21b have positive electrode active materials represented by the positive electrode active materials 17a and 17b. The positive electrode active materials 17a and 17b are filled in the pores of the metal porous body. The positive electrode active materials 17a and 17b may be nickel hydroxide, for example, but are not limited thereto.

  Negative electrodes 22a and 22b shown in FIG. 1 have negative electrode current collectors 25a and 25b, respectively. The negative electrode current collectors 25a and 25b are each made of a metal plate having through holes 15a-d. The metal plate may be, for example, an iron plate plated with nickel, but is not limited thereto. The through holes 15a-d may be formed by punching, but are not limited thereto. The through holes 15a-d may be square or round.

  The negative electrode 22a shown in FIG. 1 is provided with through holes typified by through holes 15a and 15b. On the metal plate, the through holes 15a and 15b are provided at regular intervals with respect to the alignment direction 20, which represents the vertical direction in the figure. The remaining portions 16a-c of the metal plate are located around the through holes 15a, 15b of the negative electrode 22a.

  The negative electrode 22b shown in FIG. 1 is provided with through holes typified by through holes 15c and 15d. On the metal plate, the through-holes 15 c and 15 d are provided at regular intervals with respect to the alignment direction 20. The remaining portions 16d-f of the metal plate are located around the through holes 15c, d of the negative electrode 22b.

  The negative electrode active materials 24a and 24b shown in FIG. 1 cover the negative electrode current collectors 25a and 25b, respectively. The negative electrode active materials 24a and 24b are filled in the through holes 15a-d, respectively. The negative electrode active materials 24a and 24b are preferably hydrogen storage alloys.

  FIG. 2 is a cross-sectional view of a positive electrode represented by the positive electrodes 21a and 21b and a negative electrode represented by the negative electrodes 22a and 22b. The positive electrode and the negative electrode are stacked in parallel with each other. A plurality of positive electrodes and a plurality of negative electrodes are alternately stacked one by one. Separators represented by separators 23a and 23b are disposed between the positive electrode and the negative electrode.

  FIG. 3 shows the secondary battery 40 of the present embodiment. In the figure, the description of the electrolytic solution and the case is omitted. Each negative electrode of the secondary battery 40 is composed of a plate-shaped negative electrode current collector 25a, b and other plate-shaped negative electrode current collectors. The positive electrode current collector not shown is also plate-shaped. The thickness of these current collectors is not particularly limited. Both the negative electrode and the positive electrode are plate-shaped. The thickness of these electrodes is not particularly limited.

  As shown in FIG. 3, the secondary battery 40 is preferably formed by laminating plate-like electrodes. In the present embodiment, the secondary battery is preferably not a wound battery. The secondary battery is preferably not a single-layer sheet type battery in which a single positive electrode current collector and a single negative electrode current collector are superposed.

  Returning to FIG. As shown in FIG. 1, in the set of negative electrodes 22 a and b, the through holes 15 a and b and the through holes 15 c and d are staggered in the alignment direction 20. The same applies to the other negative electrode sets shown in FIGS. For example, the through holes may be different from each other between the odd-numbered negative electrode and the even-numbered negative electrode.

  As shown in FIG. 1, the through holes 15a, 15b of one negative electrode 22a face the remaining portions 16e, f of the other negative electrode 22b, respectively. Similarly, the through holes 15c and d face the remaining portions 16a and 16b, respectively.

  In each of the negative electrodes 22a and 22b shown in FIG. 1, the interval between the through holes typified by the through holes 15a and 15b is equal to the interval between the through holes typified by the through holes 15c and 15d. The deviation between the through holes 15a, b of the one negative electrode 22a and the through holes 15c, d of the other negative electrode 22b is preferably half of the interval.

  The same applies to the other negative electrode sets shown in FIGS. For example, the interval between the through holes may be equal between the odd-numbered negative electrode and the even-numbered negative electrode. Further, the displacement of the through hole may be half of the interval. Further, when the interval between the through holes is assumed to be 360 °, the displacement of the through holes can be considered to be 180 °.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

  The positive electrode current collectors of the positive electrodes 21a and 21b shown in FIG. 2 may be made of a metal plate having through holes, similarly to the negative electrode current collectors 25a and 25b. Therefore, at least one of the positive electrode current collector and the negative electrode current collector may be formed of a metal plate having a through hole. The pair of the positive electrodes 21a and b is adjacent to each other with the negative electrode 22b interposed therebetween. In such a set, the through holes of the positive electrode may be staggered in the vertical direction, similar to the through holes 15a-d shown in FIG.

  In this embodiment, by making the through-holes of the current collector alternate in one of the positive electrode and the negative electrode, unevenness of the function of the active material is suppressed in the active material layer of the other electrode parallel to the current collector.

[Example 1]
FIG. 3 is a perspective view of the secondary battery 40 according to the first embodiment. The secondary battery 40 includes a positive electrode, a negative electrode, and a separator. In the drawing, only the negative electrode current collector represented by the negative electrode current collectors 25a and 25b is depicted. The secondary battery 40 further includes a positive current collector 29 and a negative current collector 30. The current collector 30 is connected to the negative electrode current collector. The current collector is thicker than the current collector, and the current flowing through the current collector is concentrated in the current collector.

  The through holes represented by the through holes 15a and 15b shown in FIG. 3 are regularly arranged in the vertical and horizontal directions. The mesh 18 is formed by these through holes. The mesh 18 has a lattice shape. The mesh 18 may be zigzag as described later. The negative electrode current collector 25a is rectangular.

  FIG. 4 shows metal plates 26a and 27a constituting the negative electrode current collectors 25a and 25b. The metal plate 26a shown on the upper left side constitutes the negative electrode current collector 25a. The metal plate 27a shown on the upper right side constitutes the negative electrode current collector 25b. The lower row represents the superposition of the metal plates 26a and 27a.

  A current collector 30 is provided at one end of each of the negative electrode current collectors 25a and 25b shown in FIG. The metal plates 26a and 27a are preferably rectangular. A current collector 30 is provided on one side of the rectangle. The current collecting unit 30 is preferably strip-shaped. The current collector 30 may be made of nickel, but is not limited thereto.

  An axis parallel to the direction away from the current collector 30 shown in FIG. The axis orthogonal to the X axis is taken as the Y axis. In the following, the X axis is orthogonal to the extending direction of the current collector 30. The Y axis is parallel to the extending direction of the current collector 30.

  As shown in FIG. 4, the alignment direction 20 in which the through holes are staggered is a direction parallel to the X axis. The current collector 30 is preferably parallel to the alignment direction 20. The through holes 15 a and 15 b and the through holes 15 c and 15 d are shifted from each other along the alignment direction 20. Each through hole is a rectangle elongated in the Y-axis direction.

[Specific application example 1]
FIG. 5 is an enlarged cross-sectional view of the positive electrode 21a and the negative electrodes 52a and 52b. The pair of negative electrodes 52a and 52b are adjacent to each other with the positive electrode 21a interposed therebetween. Unlike FIG. 1, the negative electrodes 52a and 52b both have the same negative electrode current collector 25a. In the set of negative electrodes 52a and 52b, the through holes face each other. Further, the negative electrode current collector 25a is also used in other negative electrodes. Therefore, the through holes face each other between all the negative electrodes.

[Contrast between Example 1 and Comparative Example 1]
As shown in FIG. 5, the positive electrode active material 17b according to Comparative Example 1 is farther from the remaining portions 16a of the negative electrodes 52a and 52b than the positive electrode active material 17a. Therefore, the positive electrode active material 17b is less likely to react than the positive electrode active material 17a.

  As shown in FIG. 1, the positive electrode active material 17b according to Example 1 is farther from the remaining portions 16a of the negative electrode 22a than the positive electrode active material 17a. However, the positive electrode active material 17b is closer to each remaining portion 16e of the negative electrode 22b than the positive electrode active material 17a. This is because the through holes of the negative electrode current collectors 25a and 25b are alternately arranged.

  Since the through holes 15a-d are staggered as shown in FIG. 1, the remaining portions 16a-d are also staggered. As a result, the positive electrode active material at an arbitrary point is close to either of the negative electrode current collectors 25a and 25b. Accordingly, it is difficult for the positive electrode active material 17a and the positive electrode active material 17b to be easily reacted. For this reason, the nonuniformity of the function of the positive electrode active material can be suppressed.

[Example 2]
In the following Examples 2 to 7, a secondary battery in which the configuration of the negative electrode current collectors 25a and 25b is different from that of Example 1 will be described. FIG. 6 shows metal plates 26b and 27b constituting the negative electrode current collectors 25a and 25b according to the second embodiment. The metal plate 26b constitutes the negative electrode current collector 25a. The metal plate 27b constitutes the negative electrode current collector 25b. The metal plates 26b and 27b are different from the metal plates 26a and 27a (FIG. 4) in that they are arranged in a staggered manner.

[Example 3]
FIG. 7 shows metal plates 26c and 27c constituting the negative electrode current collectors 25a and 25b according to the third embodiment. The upper left metal plate 26c constitutes the negative electrode current collector 25a. The lower left metal plate 27c constitutes the negative electrode current collector 25b. The right side shows the overlap of the metal plates 26c and 27c.

  As shown in FIG. 7, the alignment direction 20 in which the through holes are staggered is a direction parallel to the Y axis. The current collector 30 is preferably perpendicular to the alignment direction 20. The through holes 15 a and 15 b and the through holes 15 c and 15 d are shifted from each other along the alignment direction 20.

[Example 4]
FIG. 8 shows metal plates 26d and 27d constituting the negative electrode current collectors 25a and 25b according to the third embodiment. The upper left metal plate 26d constitutes the negative electrode current collector 25a. The lower right metal plate 27d constitutes the negative electrode current collector 25b.

  Between the metal plate 26d and the metal plate 27d shown in FIG. 8, the through holes are shifted in both the X direction and the Y direction. In other words, the alignment direction in which the through holes are staggered in this embodiment is both a direction parallel to the X axis and a direction parallel to the Y axis. The metal plates 27a and 27c are drawn for convenience in order to easily understand that the displacement of the through hole of the metal plate 27d occurs in the X direction as well as the Y direction.

  As shown in Examples 1, 3 and 4, the alignment direction in which the through holes are staggered is preferably at least one of a direction parallel to the X axis and a direction parallel to the Y axis.

[Example 5]

  FIG. 9 shows the metal plates 31 and 32 constituting the negative electrode current collector. The metal plate 31 shown on the upper left side includes through holes 33 a and 33 b that are arranged in parallel with the alignment direction 20. The metal plate 32 shown on the upper right side includes through holes 34 a and 34 b that are arranged in parallel with the alignment direction 20. The set of negative electrode current collectors shown in the lower part is formed by superimposing a metal plate 31 and a metal plate 32.

  As shown in FIG. 9, in the present embodiment as well as the first embodiment, the alignment direction 20 in which the through holes are staggered is a direction parallel to the Y axis. In the present embodiment, the proportion of the through holes in the metal plate increases as the distance from the current collector 30 increases in the direction parallel to the X axis.

  FIG. 9 shows that the opening related to the through hole becomes sparser as the distance from the current collector 30 is smaller. Moreover, it has shown that the opening which concerns on a through-hole becomes dense, so that the distance from the current collection part 30 is large. In the current collector, the current is generally denser as it is closer to the current collector 30, but in this embodiment, the current density in the vicinity of the current collector can be suppressed, so that it is easy to increase the battery output. .

[Example 6]
FIG. 10 shows metal plates 36 and 37 constituting the negative electrode current collector. The metal plate 36 shown on the upper left side includes through holes 38 a and 38 b that are arranged in parallel with the alignment direction 20. The metal plate 37 shown on the upper right side includes through holes 39a and 39b arranged in parallel with the alignment direction 20. The set of negative electrode current collectors shown in the lower part is formed by superimposing a metal plate 36 and a metal plate 37.

  As shown in FIG. 10, the alignment direction 20 in which the through holes are staggered is a direction parallel to the Y-axis, as in the first embodiment. In Example 6, the ratio of the through holes to the metal plates 36 and 37 increases from both sides of the metal plates 36 and 37 toward the center of the metal plates 36 and 37 with respect to the direction parallel to the X axis. In other words, in the X-axis direction, the ratio of the opening area of the through hole to the surface area of the metal plates 36 and 37 increases from both ends of the metal plate toward the center of the metal plate.

  As shown in FIG. 10, the positive current collector 29 may be disposed on the opposite side of the negative current collector 30 with the positive electrode and negative electrode laminate portions interposed therebetween. In this embodiment, the smaller the distance from the current collector of both the positive electrode and the negative electrode, the smaller the opening. Also, the larger the distance from both current collectors, the denser the opening. In the present embodiment, since current congestion in the vicinity of both positive and negative current collectors can be suppressed, it is easy to increase battery output and battery capacity.

[Example 7]
FIG. 11 shows the superposition of the metal plates 41 and 42 constituting the negative electrode current collector. The metal plate 41 shown on the front side includes a plurality of rows of through holes represented by the through holes 43. Adjacent rows intersect each other at the center of the metal plate 41. The intersecting angle is represented by angle A.

  The metal plate 42 hidden behind the metal plate 41 includes a plurality of rows of through holes represented by the through holes 44. Adjacent rows intersect each other at the center of the metal plate 42. The intersecting angle is the same as that of the metal plate 41. The rows of the through holes of the metal plates 41 and 42 are shifted by a predetermined angle B. Angle B is greater than 0 and less than angle A. The angle B is preferably half of the angle A.

[Simulation analysis]
The resistance values of the secondary batteries according to Examples 1 and 3 and Comparative Example 1 were analyzed by computer simulation. Details of the simulation and the analysis model will be described later.

  FIG. 12 shows an element division diagram of the analysis model. In this element division diagram, the negative electrode current collectors 25a and 25b and other negative electrode current collectors and one current collector 30 connected thereto are divided into a plurality of elements. The element division diagram also represents nodes. Table 1 shows the number of nodes and the number of elements in each example.

  Table 1 further shows the resistance values. The resistance value is the direct current of such a unit cell when a positive electrode current collector and a negative electrode current collector are stacked via a separator, and the current collector is connected to the case together with the electrolytic solution to produce a unit cell. It is the value of internal resistance (DCIR). Further, the ratio of resistance values (resistance ratio) when the internal resistance of Comparative Example 1 is 100 is shown in the lowest stage of Table 1.

  FIG. 13 is a graph showing the resistance ratio. As shown in the tables and figures, the resistance value in the example was lower than that in the comparative example. Such analysis results show that staggering the through-holes suppresses current crowding and improves battery output. These results suggest that staggering the through-holes between the negative electrodes suppresses the unevenness of the active material in the active material layer of the positive electrode parallel to the negative electrode current collector.

  Further, in Example 3, the resistance value was further reduced as compared with Example 1. This means that the effect of improving the current density is higher when the through holes are staggered in the direction perpendicular to the current collector than when the through holes are staggered in the direction parallel to the current collector. Indicates.

  Details of the simulation will be described. The above simulation simulates the influence of the distribution of through-holes on the negative electrode conductor made of punching metal, that is, the position of the openings on the current distribution in the remaining part of the through-holes. A preferred embodiment of the aperture distribution is derived by finite element method simulation. Scryu / tetra (registered trademark) was used as software.

  Details of the analysis model will be described. The width W (FIG. 3) of the negative electrode current collector in the analysis model was 25.5 mm. As a result of using six negative electrode current collectors as shown in FIG. 3, the number of positive electrodes sandwiched between the negative electrode current collectors was five. Therefore, there are five negative electrode-positive electrode-negative electrode pairs. Table 2 shows the physical property values of each member constituting the secondary battery.

  The separator was polypropylene (PP).

  The width of the negative electrode current collector of the actual model corresponding to the analysis model was 80 mm. There were 12 negative electrode-positive electrode-negative electrode pairs. (80 / 25.5) × (5/12) = 1.31 was used as the conversion factor of resistance value (actual model / analysis model). The resistance value in Table 1 represents the resistance value of the actual model calculated based on the resistance value of the analysis model.

When the conductivity of the negative electrode active material in the analysis model is 3.0 × 10 ⁵ (S / m), the resistance value (mΩ) is 1.96 (mΩ) when the resistance value (mΩ) is converted with the above conversion factor, and the resistance of the negative electrode active material in the actual model The value was close to about 2.0 mΩ. Based on this, as shown in Table 2, the conductivity of the negative electrode active material was set to 3.0 × 10 ⁵ (S / m).

  The positive electrode current collector is a metal porous body, and the positive electrode active material is dispersed in the positive electrode current collector. In the analysis model, the positive electrode made of the positive electrode current collector and the positive electrode active material is regarded as uniform. In addition, the electrical resistance value and conductivity of the positive electrode itself are analyzed as being the same as those of the negative electrode active material.

15a-d through-hole, 16a-f remaining portion, 17a, b positive electrode active material, 18 mesh, 20 alignment direction, 21a, b positive electrode, 22a, b negative electrode, 23a, b separator, 24a, b negative electrode active material, 25a, b Negative current collector, 26a-d, 27a-d Metal plate, 29, 30 Current collector, 31, 32 Metal plate, 33a, b, 34a, b Through hole, 36, 37 Metal plate, 38, 39 Metal plate , 40 Secondary battery, 41, 42 Metal plate, 43, 44 Through hole, 52a Negative electrode

Claims (8)

A positive electrode having a plate-shaped positive electrode current collector;
A negative electrode having a plate-like negative electrode current collector,
A plurality of the positive electrodes and a plurality of the negative electrodes are alternately stacked one by one,
At least one of the positive electrode current collector and the negative electrode current collector is formed of a metal plate having a through hole,
The through holes are provided at regular intervals on the metal plate with respect to a predetermined alignment direction,
Satisfy at least one of the following:
In the set of negative electrodes adjacent to each other across the positive electrode, the through holes provided in each negative electrode are staggered in the alignment direction; and the positive electrodes adjacent to each other across the negative electrode In the set, the through holes provided in each positive electrode are staggered in the alignment direction;
Secondary battery. The positive electrode has a positive electrode active material,
The positive electrode current collector is made of a metal porous body, and the positive electrode active material is filled in pores of the metal porous body,
The negative electrode current collector is made of the metal plate,
The through holes of the negative electrodes adjacent to each other across the positive electrode are staggered in the alignment direction,
The secondary battery according to claim 1. The through hole of one of the negative electrodes is opposed to the remaining metal plate around the through hole of the other negative electrode,
The secondary battery according to claim 2. In the set of negative electrodes, the intervals of the through holes are equal to each other,
The deviation between the through hole of one of the negative electrodes and the through hole of the other negative electrode is half of the interval.
The secondary battery according to claim 2 or 3. A current collector provided at one end of the negative electrode current collector;
The axis parallel to the direction away from the current collector is the X axis,
When the axis perpendicular to the X axis is the Y axis,
The alignment direction in which the through holes are staggered is at least one of a direction parallel to the X axis and a direction parallel to the Y axis.
The secondary battery in any one of Claims 2-4. The alignment direction in which the through holes are staggered is a direction parallel to the Y axis.
The secondary battery according to claim 5. With respect to the direction parallel to the X axis, as the distance from the current collector increases, the proportion of the through hole in the metal plate increases.
The secondary battery according to claim 6. In the direction parallel to the X axis, the proportion of the through hole in the metal plate increases from both sides of the metal plate toward the center of the metal plate.
The secondary battery according to claim 6.

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